Interpreting sleep studies

Overview

Each 'Level 1' sleep study performed by SNORE Australia includes a comprehensive, 3-page sleep study report that is sent to the referring doctor. The sleep study report routinely includes the following:

  • Patient details, summary of relevant measurements, sleep-related complains and medical history
  • Sleep-related diagnoses, including colour print-out from patient sleep-study data; where appropriate, abnormal brain wave activity, abnormal respiratory events and abnormal leg movements are outlined)
  • Personalised treatment recommendations based on polysomnogram findings and detailed patient history; our recommendations are based on up-to-date treatment guidelines and evidence based medicine
  • Detailed sleep-statistics, calculated after the polysomnogram has been fully analysed by experienced Sleep Study Scorers
  • Detailed respiratory statistics, snoring volumes and oxygen saturation profile
  • CPAP titration reports contain an overview of CPAP changes during the night, along with specific CPAP pressure and mask recommendations
An example of an overnight diagnostic sleep study report can be found here.
An example of an overnight CPAP titration sleep study report can be found here.

 

Sleep Study Scoring

All SNORE Australia Sleep Studies are individually analysed by experienced Sleep Study Scorers. Our senior staff are registered sleep technologists with the BRPT (Board of Registered Polysomnographic Technologists), an internationally recognised qualifcation in sleep technology. Studies are analysed according to international standards outlined by the AASM (American Academy of Sleep Medicine), ASA (Australian Sleep Association) and ASTA (Australian Sleep Technologists Association).  

 

Legend for Acronyms Commonly Used in Sleep Study Reports

Arousal: abrupt shift of EEG frequency during sleep, including alpha, beta, theta and/or higher frequencies for >3 seconds and preceded by at least 10 seconds of sleep. Arousals can occur during NREM and REM sleep

BMI: Body Mass Index (indicator of healthy body weight based on patients height)

CPAP: continuous positive airway pressure

ESS: Epworth Sleepiness Score (indicator of subjective daytime sleepiness)

Level 1: highest international standard of polysomnography recording

NREM sleep: non-rapid eye movement sleep

REM sleep: rapid eye movement (dream) sleep

REM-latency: time from sleep-onset to the first period of REM sleep

Sleep-latency: time from lights off to first period of sleep - this is essentially how long it takes for a patient to get to sleep

Sleep-related history: symptoms and information, as reported by patient

Respiratory Event Types:

Central apnoea: ≥90% reduction in peak thermal excursion from baseline, lasting at least 10 seconds; central apnoeas are associated with absence of inspiratory effort throughout the entire period of absent airflow

Obstructive apnoea: ≥90% reduction in peak thermal excursion from baseline, lasting at least 10 seconds; obstructive apnoeas are associated with continued or increased effort throughout the entire period of absent airflow

Mixed apnoea: ≥90% reduction in peak thermal excursion from baseline, lasting at least 10 seconds; mixed apnoeas are associated with absence of inspiratory effort at the start of the event, followed by return of inspiratory effort during the second portion of the event

Hypopnoea: ≥30% reduction in nasal pressure signal from baseline, lasting at least 10 seconds; hypopnoeas are associated with an oxygen desaturation of at least 3% and/or an EEG arousal

RERA: sequence of breaths lasting 10 seconds or more, with increasing respiratory effort or flattening of the nasal pressure signal leading to an EEG arousal during sleep (scored when criteria for hypopnoea is not met

AHI: Apnoea Hypopnoea Index, indicates severity of sleep-disordered breathing; ≤5 = normal; 6-14 = mild; 15-29 = moderate; ≥30 = severe